DISEASE CHARACTERISTICS: Diagnosis of metastatic breast cancer Measurable or evaluable disease Postmenopausal No spontaneous menses for at least 5 years (including chemotherapy-induced amenorrhea) Spontaneous menses within the past 5 years allowed if amenorrheic for at least 12 months and LH and FSH in postmenopausal normal range (including chemotherapy-induced amenorrhea) Bilateral oophorectomy Radiotherapy castration and amenorrheic for at least 3 months Hormone receptor status: Estrogen-receptor (ER) and/or progesterone-receptor (PR) positive No ER and PR negative or unknown tumors